One of the more preferred methods of controlling weeds in crops involves the post-emergent control of weeds wherein herbicide(s) are applied after the crop in question has emerged from the soil. Post-emergent control is desirable as it requires the application of herbicide only where an infestation of weeds is present. In contrast, pre-emergent control requires the application of herbicide early in the growing season before most weeds have germinated, with the result that such chemicals must be employed throughout a field even if they would ultimately not be needed.
p-Hydroxyphenylpyruvate dioxygenase (HPPD) is an enzyme found in both plants and animals, which catalyzes the catabolism of the amino acids phenylalanine and tyrosine. Inhibition of this enzyme has profound effects on plants, affecting the formation of homogentisic acid which is a key precursor for the biosynthesis of both tocopherols (vitamin E) and plastoquinone, a critical co-factor in the formation of carotenoids, which protect chlorophyll in plants from being destroyed by sunlight. Mesotrione is a herbicide that works by inhibiting HPPD.
Red rice is a weed that infests cultivated rice growing areas in the United States. It is a wild rice type that competes with cultivated rice for nutrients, water, and space. Presently, there is a need for a method for controlling the growth of red rice without harming the cultivated rice.